We shall use full field electro-retinography and visual evoked cortical response detection facilitated by electronic computer techniques to examine the pathophysiology of well defined forms of RP, autosomal dominant, autosomal recessive, and sex-linked forms of the disease, in cooperating and dedicated human subjects. The mechanism of adaptation of the cone electroretinogram (ERG) and visual evoked response (VER) will be studied during and after a full field adapting light of known brightness is on and then turned off the retina. The time course of recovery of the slope and amplitude of the a-wave, and the amplitude and implicit time of the b-wave of the cone ERG will be determined. The experiments will be done at several brightness levels and all will be compared with the cone ERG of normal subjects of comparable ages to the RP patients. In this way we hope to gain insight into the mechanism of cone (and possibly rod) adaptation in this disease. Additional support is requested to continue to follow on a monthly basis selected patients with RP in order to determine how reliable the cone ERG and VER are and can be made to be, the latter by following up clues to non-stationarity in the cone ERG we have discovered in our previous research.